1. Field of the Invention
The present invention relates to a semiconductor device comprising a protective element and a method of manufacturing the semiconductor device.
2. Description of the Related Art
In recent years, with a change in CMOS generation, gate insulating films have become thinner. Accordingly, the application of an external high voltage may cause the gate insulating film to be easily broken down. To prevent this breakdown, a protective element is located in an input section so as to be operated to allow a current to flow before a high voltage is applied to an internal circuit.
An important point for the prevention of dielectric breakdown is the voltage at which the protective circuit starts to operate. This is because the voltage at which the internal circuit is broken down decreases as the generation changes, so that the operating voltage of the protective element must be reduced as the generation changes. However, in the prior art, means for reducing the operating voltage of the protective circuit is unknown.
Prior art document information relating to the present invention is listed below.    [Patent Document 1] Jpn. Pat. Appln. KOKAI Publication No. 11-274404    [Patent Document 2] Jpn. Pat. Appln. KOKAI Publication No. 2002-280552    [Patent Document 3] Jpn. Pat. Appln. KOKAI Publication No. 2003-51581